High-torque hand tool



Jan. 12, 1960 mlfillllIIIIIIIIIIIIIIIIIIIIIIIIIIIHII H. W. PIQUET HIGH-TORQUE HAND TOOL Filed Jan. 31, 1958 F/GQZ lllllllli mmw NJ 6 INVENTOR:

HENRY W. P/QUET ATZTYS- United States PatentjQ HIGH-TORQUE HANDTOOL Henry W. Piquet, Moorestown, NJ. Application January 31, 1958, Serial No. 712,416

3 Claims. or. 74-66) The present invention relates to hand tools and has particular application to screwdrivers and similar tools in which it is desired to provide a greater torque-than that provided by conventional screwdrivers.

-High-torque hand tools of the prior art are very expensive to manufacture or are rather cumbersome to use. In addition, the prior high-torque hand tools continuously operate to provide maximum torque, regardless of the requirement of the work. For example when using a screwdriver, high torque is normally only required when initially loosening the screw, and in the final stages of tightening the screw. Thus, high torque is required for only a minor portion of the work of a screwdriver, and since the multiplication of torque is accompanied by a requirement for increased rotation of the screwdriver handle to provide the given rotation offthe screwdriver bit or blade or by a loss of maneuverability, screwdrivers which constantly provide a torque multiplication are not entirely satisfactory. I With the foregoing in mind, the present invention'provides a high torque hand tool in which the multiplied torque is obtained for only a part of the operation of the tool and is automatically locked out to provide a straight drive during the remaining portion of the operation.

The invention also provides a high torque hand tool which is highly economical to manufacture and assemble, but is fully effective in operation and use.

.The invention also provides a hand tool which is compact and readily operated to provide torque multiplication.

All of the objects of the invention and the various features and details of the construction and operation thereof are more fully set forth hereinafter with reference to the accompanying drawing in which:

Fig. 1 is a view in elevation of a screwdriver embodying the present invention;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is an exploded view showing the novel elements of the screwdriver in perspective.

Fig. 4 is a sectional view taken on the line 44 of Fig. '2; and

Fig. 5 is a view similar to Fig. 4 showing the operation of the torque multiplication structure of the invention.

Referring now to the drawing, the illustrated screwdriver embodying the present invention comprises a handle 10, which may be of conventional form, mounted on a drive shaft 11. A bit or blade 12 is formed integral with a work shaft 14 which is axially aligned with the drive shaft 11. Transmission means 15 interconnects the drive shaft 11 with the work shaft 14 to aflord either torque multiplication or direct drive between the shafts.

The transmission 15 embodies a generally cylindrical housing formed by an upper cup member 17, a lower cup member 18, and an intermediate partition 19. The cup members 17 is secured to the partition 18 by a lance 21 struck out from the cup member 17 into engagement ICC 2 with a'recess22 in the partition 19. The cup 18 is secured to the assembly by displacing the rim as indicated at 23 into apertures 24 of the cup member 17 and into engagement with the periphery of the partition member 19. Further interlocking of the cup members 17 and 18 ma be provided by coining as indicated at 25.

The partition 19 is provided with an eccentric circular opening 26 to receive a circular transmission disk or rotor 27 having diametrically opposite recesses formed in its periphery as indicated at 28 and 29 respectively. The

' drive shaft 11 is formed with a drive disk 32 of circular and 14 and the housing 16. The work shaft 14 is pro-- the pin 33 is approximately one half of the turning radius R2 of the pin 36 so that a 2:1 mechanical advantage is.

configuration for rotation concentrically within the housing 16 above the partition 19. The drive disk is provided with a central depending drive pin 33 depending into the recess 28 at a point offset from the axis of the shafts 11 vided with a work disk 35 having an upwardly projecting work pin 36 engageable in the recess 29 adjacent the periphery of the housing 16.

In the operation of the transmission 15, rotation of the drive shaft 11 rotates the pin 33 about the axis A of the cylindrical casing 16. Rotation of the pin 33 within the housing causes the disk 27 to rotate about its center C which,,in turn, drives the pin 36 for rotation about the axis A. As indicated in Fig. 4, the turning radius R1 of obtained. Thus, the application of a given torque to the drive shaft 11 produces twice the torque on the work shaft '14. 'Of course, the angular displacement about the axis Act the drive pin 33 is twice that of the work pin 36,"

asindicated at D1 and D2 respectively in Fig. 5.

In accordance with the invention, the construction of the transmission 15 operates to automatically lock out the torque multiplication after a predetermined rotation of the shafts 11 and 14. In the operation of the device when unscrewing a threaded fastener, the casing 16 is held and the drive shaft 11 is rotated to the clockwise limit position indicated in broken lines in Fig. 5. Further clockwise movement is prevented by reason of the engagement of the pin 36 with the wall of the circular aperture 26 in the partition 19, the aperture 26 being eccentric to the turning axis A of the pin 36. With the transmission in this position, the work tool or bit 12 is engaged with the screw engaged in the work. Then, with the casing 16 still shaft 11. When the transmission is in the position shown in full lines in Fig. 5, the pin 36 engages against the wall of the circular aperture 26 of the partition 19 and prevents further rotation of the pins in the casing 16. Thus, the further rotation of the drive shaft 11 drives the transmission counterclockwise providing a direct connection between the shafts 11 and 14, without any torque multiplication. From this point on, the screwdriver operates as a conventional screwdriver, this being entirely satisfactory since the initial torque multiplication is normally sufficient to dislodge the screw from the work to enable the screw to be unscrewed the rest of the way without torque multiplication.

When the operation is reversed to screw a threaded fastener into a work piece, the handle is rotated clockwise, and the transmission is in the position shown in broken lines in Fig. 5. This provides a direct drive between the drive shaft 11 and work shaft 14 and the direct drive is continued until substantial resistance against further turning is encountered. At this time, the bit 12 is disengaged from the screw, and the casing 16 of the transmission 15 is held while the drive shaft 11 is rotated to its counterclockwise limit position in the casing, as shown in full lines in Fig. 5. The bit is then re-engaged with the screw and with the casing still held against rotation, the handle being rotated clockwise to turn the drive pin 33 from the full line to the broken line position of Fig. 5. This effects turning of the Work pin 36 from the corresponding positions with a torque multiplication. If, when the transmission is in its clockwise limit position, the spool is not fully seated, the final operation may be repeated until the spool is fully seated with the aid of the torque multiplication afforded by the transmission 15.

The operation of the transmission may be compared to a planetary gear assembly in which the disk 35 and pin 36 corresponds to the ring gear, the disk 32 and pin 33 corresponds to the sun gear, and the disk 27 corresponds to the planet gear. The present construction is distinguished from the planetary gear construction by reason of its greater economy in manufacture as well as the novel locking-out action aiforded by the engagement of the pin 36 with the Wall of the recess 26.

The illustrated embodiment of the invention employs a screwdriver blade as the work bit, but it is contemplated that other work bits may be employed, such as socket wrench heads, Phillips screwdn'verheads, and the like. With slight modification, of the transmission 15, the Work elements of the hand tool may be replaceable for interchangeability of parts to provide different work bits for dilferent operations While a particular embodiment of the present invention has been herein illustrated and described, it is not intended to limit the invention to such disclosure, but changes and modifications may be made therein and thereto within the scope of the following claims.

What is claimed is:

l. A- hand tool comprisinga handle and a work bit, a drive shaft on said handle, a work shaft on said work bit in axial alignment with said drive shaft, and a transmission interconnecting said drive shaft with said work shaft comprising a casing having a transverse partition therein, means defining a circular aperture in said partition eccentric to said drive and work shafts, a rotor element rotatable in said aperture, a drive pin on said drive shaft rotatable coaxially therewith and engaged with said rotor at a given distance from the turning axis of said rotor element, a work pin rigidly connected to said work shaft and rotatable in said casing about said axis and engaged with said rotor at a point a greater distance from its turning axis than said given distance and means to limit displacement of said pins radially of the axis of said rotor element to maintain said relationship whereby rotation of said drive pin through a given angular distance effects rotation of said work pin a lesser angular distance to provide a greater torque on said work shaft than applied to said drive shaft.

2. A hand tool according to claim 1 wherein said work element of the transmission is rotatable about said axis between clockwise and counterclockwise limit positions respectively engaging the wall means defining said circular aperture.

3. A hand tool according to claim 1 wherein said rotor comprises a circular disk mounted in said aperture and having opposed radial slots at diagonally opposite points on the periphery of said disk to receive respectively the drive pin and the work pin of said transmission.

References Cited in the file of this patent FOREIGN PATENTS 1,068,216 France June 23, 1954 

